The ball is the offside boundary line. Play will continue until one of three things happens: One team scores, one team commits a penalty, or the ball goes out of bounds. While the ball is in play, its spot on the field determines where each player on both teams needs to be to stay on sides.

 

Pretend there is a line that extends from the ball across the width of the field at all times. If your team has the ball, your teammates are on sides as long as they stay behind that line.

 

It’s a little different for the other team, as its players are likely coming after whoever has the ball on your team. The other team must come toward the ball-carrier straight on or at least from a forward direction. They’re not allowed to tackle the ball carrier from the side or behind.